SANTA CLARA, Calif. — For all the foot-burners on the field at Levi’s Stadium in Sunday’s NFC divisional-round playoff game between the San Francisco 49ers and Dallas Cowboys, it was becoming a battle of attrition, turnovers, field position, old-school defense and — swallow hard — kickers. Both teams had weapons, but both had stoppers, and you wondered whether this was going to be decided by inches or by somebody’s foot. Instead, George Kittle made something so big happen, a catch so eye-widening and lore-worthy, that it rescued this stingy small-yardage game and helped vault the 49ers to the NFC championship game by the suggestively grudging score of 19-12.